Effect of dietary inclusion of Moringa oleifera Lam leaf meal on feed
conversion efficiency, meat quality, fatty acid composition, shelf life and
consumer health-related perceptions of pork
By
Felicitas Esnart MUKUMBO
A Dissertation submitted in fulfilment of the requirements for the degree of MASTER OF SCIENCE IN AGRICULTURE (ANIMAL SCIENCE)
in the
Department of Livestock and Pasture Science Faculty of Science and Agriculture
Alice, South Africa
December 2013
Supervised by: V. Maphosa
i
Effect of dietary inclusion of Moringa oleifera Lam leaf meal on feed
conversion efficiency, meat quality, fatty acid composition and shelf life of
pork and consumer health related perceptions on pork and fatty acids
By
Felicitas Esnart MUKUMBO
A Dissertation submitted in fulfilment of the requirements for the degree of MASTER OF SCIENCE IN AGRICULTURE (ANIMAL SCIENCE)
in the
Department of Livestock and Pasture Science Faculty of Science and Agriculture
Alice, South Africa
December 2013
Supervised by: V. Maphosa
i Declaration
I, Felicitas Esnart Mukumbo, vow that this dissertation has not been submitted to any
University and that it is my original work conducted under the supervision of Dr V. Maphosa
and Prof. V. Muchenje. All assistance towards the production of this work and all references
contained herein have been duly accredited.
___________________________ ________________________
Felicitas Esnart Mukumbo Date
Approved to style and content by:
___________________________ ______________________________
Dr V. Maphosa (Supervisor) Prof. V. Muchenje (Co-supervisor)
ii Abstract
Effect of dietary inclusion of Moringa oleifera Lam leaf meal on feed conversion
efficiency, meat quality, fatty acid composition, shelf life and consumer health-related perceptions of pork
By
Felicitas E.Mukumbo
The objective of the study was to determine the feed conversion efficiency (FCE), carcass
characteristics, physico-chemical quality, fatty acid (FA) composition and shelf life of pork
from pigs fed diets containing either 0% (T1), 2.5% (T2), 5% (T3) or 7.5% (T4) Moringa
oleifera leaf meal (MOLM). Consumer health-related perceptions on pork and fatty acids
were also investigated. Twenty four crossbred Large White x Landrace pigs of both sexes at
18 weeks of age and initially weighing 71.6 kg on average were housed individually and had
ad libitum access to one of the four dietary treatments for a period of six weeks. Average
daily feed intake (ADFI) and average daily gain (ADG) and feed conversion ratios (FCR)
were calculated as an indication of FCE and pigs were slaughtered at an average live weight
of 99.6 kg. Carcass traits such as back fat thickness (BFT), carcass temperatures and pH
readings taken 45 minutes and 24 hours (pH45 and pHu) post mortem were recorded. M.
longissimus thoracis et lumborum (LTL) samples were taken from each carcass for the
determination of lightness (L*), redness (a*), yellowness (b*), thawing loss percentage
(TL%), cooking loss percentage (CL%), Warner Bratzler Shear Force (WBSF), shelf life and
FA composition. Furthermore a survey was conducted amongst 80 University of Fort Hare
Students to determine their health-related perceptions on pork and fatty acids as well as their
pork consumption frequency using questionnaires. The FCE of pigs fed on 0-5% MOLM (T1,
iii significantly (p<0.05) reduced. No significant relationship was reported between inclusion of
MOLM carcass characteristics and physico-chemical pork quality. There was however a
significant improvement (p<0.05) in the shelf life of the pork from MOLM fed pigs in terms
of colour and odour during 10 days of refrigerated storage (at 3±1°C). There was a significant
(p<0.05) reduction in the total intramuscular fat (IMF) content and the saturated fatty acid
(SFA) C18:0 (stearic acid) content and an overall non-significant (p>0.05) increase in the
poly unsaturated fatty acid (PUFA) content of pork from MOLM fed pigs. The possible
reason for this is that the feeding of MOLM was commenced when the pigs were at an
advanced age and weight. The survey revealed that the majority of interviewed students
consume fresh (39.7%) and processed (32.4%) pork two to three times a week, perceive pork
to be generally healthy (70%) and the second most healthy meat type (39.5%). While the
majority (55.4%) were aware of the health implications of FAs they did not know which FA
classes pose more of a health risk (51.3%). In conclusion2.5% and 5% of MOLM in finisher
pig feed did not negatively affect FCE, carcass characteristics or physico-chemical meat
quality; significantly improved pork shelf life and reduced total IMF and SFA content of pork
but 7.5% MOLM negatively affected FCE; and the majority of students perceive pork to be
the second most healthy type of meat and are generally aware of the health implications of
FAs.
Key words: Moringa oleifera, feed conversion efficiency, physico-chemical meat quality,
iv List of abbreviations
a* - Redness
ADFI – Average daily feed intake
ADG – Average daily gain
b* - Yellowness
CL% - Cooking loss percentage
FCE – Feed conversion efficiency
FCR – Feed conversion ratio
IA – Index of atherogenicity
IMF – Intramuscular fat
IT – Index of thrombogenicity
L* - Lightness
LTL - M. longissimus thoraciset lumborum
MOLM – Moringa oleifera leaf meal
MUFA – Monounsaturated fatty acid
PUFA – Polyunsaturated fatty acid
SCF – Subcutaneous fat
SFA – Saturated fatty acid
TL% - Thawing loss percentage
v Table of Contents
Declaration ... i
Abstract ... ii
List of abbreviations ... iv
List of tables ... viii
List of figures ... ix List of Appendices ... x Acknowledgments ... xi CHAPTER 1: Introduction ... 3 1.1 Background ... 3 1.2 Problem Statement ... 5 1.3 Justification ... 6 1.4 Objectives ... 6 1.5 Hypotheses ... 7 1.6 References ... 12
CHAPTER 2: Literature Review ... 17
2.1 Introduction ... 17
2.2 Uses of Moringa oleifera in agriculture ... 19
2.3 Nutritional composition of Moringa oleiferaleaves ... 20
2.4 Effect of nutrition on pig production and pork quality ... 23
2.4.1 Growth ... 23
2.4.2 Carcass characteristics ... 25
2.4.3 Meat quality ... 25
2.5 Fat composition ... 28
2.6Shelf life ... 30
2.7 Consumer perception and preferences on pork ... 30
2.7.1 Health implications of pork consumption ... 32
2.7.2 Consumer perceptions on pork ... 33
vi
2.8 Summary of review ... 38
2.9 References ... 40
Chapter 3: Effect of dietary inclusion of ground Moringa oleifera leaves on feed conversion efficiency, meat quality and shelf life of pork ... 52
Abstract ... 52
3.1 Introduction ... 54
3.2 Methodology ... 57
3.2.1 Study Site description ... 57
3.2.2 Dietary treatments ... 57
3.2.3 Animal management ... 57
3.2.4 Productivity parameters and slaughter ... 58
3.2.5 Carcass weights, back fat thickness, pH, temperature ... 61
3.2.6 Meat samples ... 62
3.2.7 Colour measurements ... 62
3.2.8 Thawing loss and cooking loss ... 62
3.2.9 Warner Bratzler Shear Force determination ... 63
3.2.10 Shelf life ... 63
3.2.11 Statistical analysis ... 64
3.3 Results and discussion ... 65
3.3.1 Feed conversion efficiency and carcass traits ... 65
3.3.2 Physico-chemical meat quality ... 70
3.3.3 Shelf life ... 72
3.4 Conclusion ... 78
3.5 References ... 79
Chapter 4: Fatty acid composition of pork from pigs fed Moringa oleifera leaf meal ... 84
Abstract ... 84
4.1 Introduction ... 85
4.2 Methodology ... 87
4.2.1 Study site and animal management ... 87
vii
4.2.3 Determination of fat profiles of feed materials and pork samples ... 87
4.2.4 Indices of lipid quality ... 90
4.2.5 Statistical analysis ... 90
4.3 Results and discussion ... 92
4.3.1 Subcutaneous fatty acid composition ... 92
4.3.2 Intramuscular fatty acid composition ... 92
4.3.3 Health lipid indices ... 99
4.4 Conclusion ... 102
4.5 References ... 103
Chapter 5: Consumer health related perceptions on pork and fatty acids ... 107
Abstract ... 107
5.1 Introduction ... 108
5.2 Methodology ... 110
5.2.1 Survey on health-related perceptions on pork and fatty acid and pork consumption ... 110
5.2.2 Statistical analysis ... 110
5.3 Results and discussion ... 112
5.3.1 Association between demographic characteristics and pork consumption ... 112
5.3.2 Students frequency of pork consumption and health-related perceptions on pork ... 116
5.3.3 Ranking of meat types and fatty acids according to perceived healthiness ... 121
5.4 Conclusion ... 124
5.5 References ... 125
Chapter 6: General discussion, conclusions and recommendations ... 127
6.1 General discussion ... 127
6.2 Conclusions ... 129
6.3 Recommendations ... 130
viii List of tables
Table 2.1 Nutritional composition of Moringa oleifera leaves...22 Table 3.1 Composition of dietary treatments on as fed basis...54 Table 3.2 Proximate and mineral composition of experimental feeds and MOLM,
on dry matter basis...55 Table 3.3 Effect of dietary treatment on feed conversion efficiency and carcass
characteristics...62 Table 3.4 Effect of dietary treatment on physico-chemical meat quality traits ...66 Table 3.6 Effect of treatment on instrumental colour measurements over
ten days of refrigerated storage...72 Table 4.1 Fatty acid composition of experimental dietary treatments and
Moringa oleifera leaf meal...88 Table 4.2 Effect of dietary treatment on fatty acid composition of
subcutaneous fat...94 Table 4.3 Effect of dietary treatment on total % fatty acid composition
of longissimus thoracis muscle ...96 Table 4.4 Effect of dietary treatment and sex on health lipid indices of
subcutaneous fat and intramuscular fat...100 Table 5.1 Demographic information of the interviewed students according to gender,...114 age and tribe
Table 5.2 Associations between students‟ demographic information and pork...115 consumption habits and health related perceptions on meat and fatty acids
Table 5.3 Frequency of pork and pork products consumption and health ...119 related perceptions on pork and fatty acids
Table 5.4 Association between health related perceptions on pork ...120 and frequency of consumption of fresh pork processed pork on a weekly basis
ix List of figures
Figure 2.1 Possibilities to imporve characteristics, consumer perception and
acceptability of pork………...…..36
Figure 3.1 Effect of dietary treatment over time on senosry apraisal of pork
colour during 10 days of refrigerated storage………..68
Figure 3.2 Effect of dietary treatment over time on senosry apraisal of pork
odour during 10 days of refrigerated storage………..…….…69
Figure 4.1Subcutaneous fat, fat-free dry matter and moisture composition of
subcutaneous fat samples as affected by sex...93
Figure 4.2 Intramuscular fat content, fat-free dry matter and moisture
composition of Longissimus thoracis muscle samples as affected by sex...95
Figure 5.1 Ranking of meat types from most to least healthy...122
x List of Appendices
xi Acknowledgments
I would like to acknowledge and extend thanks to all who contributed to the compilation of
this work. Much gratitude goes out to my supervisors Dr V. Maphosa and Prof. V. Muchenje
for their support, guidance, input and encouragement and to Prof. A Hugo, Dr T. Nkukwana
and Mr T. Mabusela for their valuable assistance and their expertise. Many thanks go out to
Mr D. Pepe, Ms N. Moko, Dr Moyo, Dr J. Madzimure and Ms P. Nakalabi for technical
assistance. Special thanks go out to the management, staff and students of Fort Cox College
of Agriculture and Forestry for the use of their facilities and their hospitality during my stay
with them, with special recognition going out to Ms P. Nakalabi, Dr B. Moyo, Mr P. Zhivave,
Mr Manyota, Mr Mazibuko and the students for their assistance. Many thanks go out to my
colleagues for all the support rendered during my studies, with special recognition going out
to Mr L. Mapfumo, Mr C. Nantapo, Dr P. O. Fayemi, Mr J. Menzi, Mr D. Sivuyile, Ms N.
Xazela, Ms Y. Njisane, Ms C. Katiyatiya, Mr M. Nkhohla, Ms Z. Gobane, Ms B. Gunya, Ms
R. Zikhona, Ms X. Nduku, Ms L. Gwala, Mr S. Soga, Mr S. Simanga, Mr M. Gxasheka, Ms
A. Maqhashu and Mr A Kwaza.
Special appreciation goes out to the Canon Collins Educational and Legal Assistance Trust
for the scholarship covering my tuition and living costs, DST-NRF SA-Argentina Research
Collaboration for covering all research costs, NRF SARChI Chair in Meat Science-Genomics
to Nutrinomics for sponsoring my attendance and presentation at the 46th South African Society for Animal Science (SASAS) Congress and to Govan Mbeki Research and
Development Centre for their support and sponsoring attendance of the 45th SASAS Congress. Finally I would like to thank my wonderful parents Mr & Mrs Bryson& Jeannette
xii Dewi, my sister in law Esther and little nephew Joshua and all of my family and friends for
their unwavering support and for believing in me. I dedicate this dissertation to them and to
the late Amos Tawanda Jenami who will always be missed by those who knew him,
MHSRIP. Above all I give thanks to the Lord God Almighty for seeing me through to the
3 CHAPTER 1: Introduction
1.1 Background
Pig production is practised in most countries worldwide on varying scales. Some of the
advantages of farming with pigs are that they grow rapidly, reproduce at a fast rate and are
able to feed on a wide range of feed stuffs (Kyriazakis and Whittemore, 2006).
Characteristics such as their high fecundity, short gestation interval, high feed conversion
efficiency and relatively small space requirement (Lekule and Kyvsgaard, 2003) make pig
production economically viable. The growth performance of pigs is determined by the
interaction of a number of genetic, environmental and management factors (Lynch et al.,
2006). The hormones responsible for regulating growth are influenced by genetic, nutritive
and environmental factors (Hossner, 2005). Consequently, the growth rate of pigs‟ results
from the interaction of factors including nutrition, genotype, parental age and size, age and
sex of the individual animal and environmental temperatures (Lynch et al.,2006; Bhat et al.,
2010). Nutrition is one of the major determinants of animal growth because the provision of
adequate nutrition has a direct effect on the realisation of genetic growth potential (Wen-qian
and Fu-chang, 2010). Nutrition also has a major influence on animal health, reproduction and
the quality of the products derived from them. Like growth performance, meat quality is also
influenced by a number of factors including genetics, animal nutrition, animal handling
during transportation and slaughter and the handling of the carcass (Pettigrew and Esnaola,
2001; Dugan et al., 2003).
Meat quality is a broad concept that includes eating quality aspects such as appearance,
flavour, tenderness and juiciness; physico-chemical aspects such as pH, water holding
4 health implications and ethical acceptability (Anderson, 2000). The diet fed to a pig
influences the quality of the pork produced and can be used as a means to improve such
factors as the water binding capacity, colour, pH, fat firmness, oxidative stability and shelf
life (Pettigrew and Esnaola, 2001). Pork naturally has a higher poly unsaturated fatty acid
(PUFA) content than other types of meat because the cereal based diets that pigs consume are
high in PUFAs and the fatty acid (FA) composition of meat, especially from monogastric
animals, is greatly influenced by the FA composition of the feed consumed (Wood et al.,
2003). This is because in monogatrics FAs are absorbed by the animal unchanged unlike in
ruminants, where FAs are hydrogenated in the rumen and then absorbed (Wood et al., 2003).
Fatty acid composition is an important aspect of meat quality and it also has an influence on
other technological aspects of meat quality (Hugo and Roodt, 2007). Fatty acid composition also has a major impact on consumers‟ perspective of meat as being healthy or as a potential
risk factor. The type of fatty acids present in meat and their susceptibility to oxidation is an
important aspect that influences the shelf life of meat (Wood et al., 2003). The high PUFA
content of pork makes it more susceptible to oxidation. The inclusion of antioxidants such as
vitamin E and selenium in pig diets at levels above the dietary requirement levels can prevent
lipid oxidation in fresh pork and pork products (Rosenveld and Anderson, 2003).These
compounds occur naturally in some plant species.
Moringa oleifera Lam is a small, fast growing tree originally from Asia but now widely
grown in tropic and sub-tropic areas worldwide. It is the most widely known and used
member of the moringaceae family and is also known by some common household names
such as drumstick tree, horseradish tree and mallugnay (FAO, 2007; ECHO, 2007; Paliwal et
al., 2011). Studies have shown Moringa oleifera Lam to be of immense nutritional value,
5 notably high levels of n-3(α-linoleic acid); and to have medicinal properties (Moyo et
al.,2011). Moringa oleifera is considered to be a functional food and its addition to animal
feeds can enhance the functionality of the meat produced. Due to its nutritional
characterisation, Moringa oleifera has the potential to be a valuable resource for animal
nutrition (Reyez-Sànchez et al., 2006).
1.2 Problem Statement
Pork naturally has high levels of PUFA and this makes it more susceptible to oxidation and
which can lead to rancidity, off flavours, negative effects on the colour and a reduced shelf
life of pork. While pork naturally has a favourable PUFA:SFA ratio, nutritionists have
recently placed emphasis on the type of PUFA in the diet, specifically the balance between n
-3 PUFA (18:-3) and n-6 PUFA (18:2) because the ratio of n-6:n-3 PUFA is also a risk factor
in cancers and coronary heart disease and the formation of blood clots leading to heart attacks
(Enser, 2001; Wood et al., 2003). Pork has an unfavourably high n-6:n-3 ratio.There have
been many studies and much media coverage over the past decade concerning health and
safety issues of the human diet and one of the major issues raised with meat concerns the
fatty acid composition because saturated fatty acids (SFA) have been implicated in increasing
the risk of coronary heart diseases, diabetes mellitus, stroke and some cancers (Wood et
al.,2003; Walker et al., 2005). Consequently,consumers of meat are concerned about the
composition of meat fat. Therefore pig producers are faced with the challenge of producing
healthier meat with a more favourable n-6:n-3 ratio without having any adverse effects on the
meat quality.They are in need of alternative feed ingredients or additives that they can use in
6 1.3 Justification
Research in swine nutrition has shown that the productivity, quality of meat and fatty acid
profile of pork fat can be altered by manipulating the pigs‟ diets (Mas et al.,2010; Rentfrow
et al., 2003). All of these factors can be altered by means of incorporating feed sources that
are known to have properties that can cause the desired alteration. However, there are
restrictions on what substances can be used because consumers are concerned about the
nature of additives used, particularly those of synthetic origin (Fasseas et al., 2007; Troy and
Kerry, 2010). Moringa oleifera Lam is of natural origin so its inclusion in animal diets is not
likely to raise any consumer concerns. In addition to its nutritional potential to promote
animal productivity and favourably affect fat composition, M. oleifera also has high phenolic
content and potent antioxidant properties (Verma et al., 2009) which can have a positive
effect on meat quality and oxidative stability. Numerous studies have been conducted to
assess the functional value of feeding Moringa oleifera leaf meal (MOLM) to various animal
species including cattle (Reyes-Sánchez et al., 2005), goats (Moyo et al., 2012; Qwele et al.,
2013), chickens (Olugbemi et al., 2010; Wapi et al., 2013; Nkukwana et al., 2014) and fish
(Afuang et al., 2003; Ritcher et al., 2009). However, documented information on the dietary
use of MOLM for pigs is lacking and findings from this study will contribute towards filling
that knowledge gap.
1.4 Objectives
The aim of the study was to determine the suitability of Moringa oleifera Lam leaf meal
(MOLM) as an alternative feed source for finisher pigs by determining the effect that the
inclusion of various levels of MOLM in pig feed would have on animal productivity and on
the quality aspects of the meat. A second aim was to determine consumer perceptions on
7
to determine the effect of dietary inclusion of MOLMon feed conversion efficiency, carcass characteristics, meat quality, fatty acid composition and shelf life of pork.
to determine consumer health-related perceptions on pork and fatty acids classes 1.5 Hypotheses
The null hypotheses be tested were:
1. Dietary inclusion of MOLM has no effect on feed conversion efficiency,
physico-chemical pork quality,fatty acid composition and shelf life of pork.
12 1.6 References
Afuang, W., Siddhuraju, P. and Becker, K. 2003.Comparative nutritional evaluation of
raw, methanol extracted residues and methanol extracts of Moringa (Moringa oleifera Lam.)
leaves on growth performance and feed utilization in Nile tilapia (Oreochromis niloticus L.)
Aquaculture Research, 34: 1147-1159.
Anderson, H.J. 2000. What is pork quality? In C. Wenk, J.A. Fernandez & M. Dupuis (Eds.), Quality of meat and fat in pigs as affected by genetics and nutrition: In: Proceedings
of the joint session of the EAAP commissions on pig production, animal genetics and animal
nutrition. (pp. 15-16). Zurich, Switzerland.
Bhat, P. N., Mohan, N. H. and Deo, S. 2010. Pig Production, Global Media, Delhi, India.
Dugan, M. E. R., Aalus, J. L. and Utaro, B. 2004. Nutritional manipulation of pork quality: current opportunities. Advances in Pork Production, 15: 237-243.
ECHO.2007. The moringa tree. ECHO Technical note, Florida, USA.
http://chenetwork.org/files_pdf/Moringa.pdf. (Accessed 24 April 2012).
Enser, M. 2001. The role of fats in human nutrition.In B. Rossell (Ed.), Oils and fats, Vol. 2.Animal carcass fats.Leatherhead Publishing,Surrey, UK.
FAO.2007. Moringa oleifera.
13 Fasseas, M., Mountzouris, C. K., Tarantilis, P. A., Polissiou, M. and Zervas, G. 2007. Antioxidant activity in meat treated with oregano and sage essential oils. Food Chemistry,
106: 1188-1194.
Hossner, K. L. 2005. Hormonal regulation of farm animal growth.CABI publishing,
Oxfordshire, U.K.
Hugo, A. and Roodt, E. 2007. Significance of porcine fat quality in meat technology: a review. Food Reviews International, 23: 175-198.
42
Kyriazakis, I. and Whittemore, C. T. 2006. Whittemore‟s Science and Practice of Pig Production: Third Edition. Blackwell Publishing, Oxford, UK.
Lekule, F. P and Kyvsgaard, N. C. 2003.Improving pig husbandry in tropical resource-poor communities and its potential to reduce risk of porcine cysticercosis.Acta Tropica, 87:
111-117.
Lynch, P. B., Cahill, A., Lawlor, P., Boyle, L., O’Doherty, J. V. and LeDividich, J. 2006. Studies on growth rates in pigs and the effect of birth weight.Agriculture and Food
Development Authority.
http://www.teagasc.ie/research/reports/pigs/5220/eopr-5220.pdf.(Accessed 18 April 2012).
Mas, G., Llavall, M., Coll, D., Roca, R., Diaz, I., Gispert, M., Oliver, M. A. and Realini, C. E. 2010. Carcass and meat quality characteristics and fatty acid composition of tissues
14 from Pietrain-crossed barrows and gilts fed an elevated monounsaturated fat diet. Meat
Science, 85: 707-714.
Moyo, B., Masika, P. J., Hugo, A. and Muchenje, V. 2011.Nutritional characterization of Moringa(Moringa oleifera Lam.) leaves. African Journal of Biotechnology, 10(60): 12925-12933.
Moyo, B., Oyedemi, S., Masika, P. J. and Muchenje, V. 2012. Polyphenolic content and antioxidant properties of Moringa oleifera leaf extracts and enzymatic activity of liver from
goats supplemented with Moringa oleifera leaves or sunflower seed cake. Meat Science, 91:
441-447.
Nkukwana, T. T., Muchenje, V., Masika, P. J., Hoffman, L. C., Dzama, K., and Descalzo, A. M. 2014. Fatty acid composition and oxidative stability of breast meat from broiler chickens supplemented with Moringa oleifera leaf meal over a period of refrigeration.
Food Chemistry, 142: 255-261.
Paliwal, R., Sharma, V. and Pracheta.2011. A review on Horse Radish Tree (Moringa oleifera): A multipurpose tree with high economic and commercial importance. Asian
Journal of Biotechnology 3(4): 317-328.
Pettigrew, J. E. and Esnaola, M. A. 2001. Swine nutrition and pork quality: A review.
15 Qwele, K., Hugo, A., Oyedemi, S. O., Moyo, B., Masika, P. J., and Muchenje, V. 2013. Chemical composition, fatty acid content and antioxidant potential of meat from goats
supplemented with Moringa (Moringa oleifera) leaves, sunflower cake and grass hay. Meat
Science, 93: 455-462.
Rentfrow, G., Sauber, T. E., Allee, G. L., and Berg, E. P. 2003.The influence of diets containing either conventional corn with choice with grease, high oil corn, or high oil high
oleic corn on belly/bacon quality.Meat Science, 64: 459–466.
Ritcher, N., Siddhuraju, P. and Becker, K. 2003. Evaluation of nutritional quality of moringa (Moringa oleifera Lam.) leaves as an alternative protein source for Nile tilapia
(Oreochromis niloticus L.). Aquaculture, 217: 599-611.
Rosenvold, K. and Anderson, H. J. 2003.Factors of significance for pork quality- a review. Meat Science, 64: 219-237.
Reyes-Sànchez, N., Spörndly, E. and Ledin, I. 2006.Effect of feeding different levels of foliage of Moringa oleiferato creole dairy cows on intake, digestibility,milk production and
composition.Livestock Science, 101: 24-31.
Troy, D. J. and Kerry, J. P. 2010.Consumer perception and the role of science in the meat industry.Meat Science, 86: 214–226.
16
Verma, A. R., Vijayakumar, M., Mathela, C. S. and Rao, C. V. 2009.In vitro and in vivo
antioxidant properties of different fractions of Moringa oleifera leaves.Food and Chemical
Toxicology, 47: 2196-2201.
Walker, P., Rhubart-Berg, P., McKenzie, S., Kelling, K. and Lawrence, R. S. 2005.Public health implications of meat production and consumption.Public Health
Nutrition,8(4): 348–356.
Wapi, C., Nkukwana, T. T., Hoffman, L. C., Dzama, K., Pieterse, E., Mabusela, T., and Muchenje, V. 2012. Physico-chemical shelf-life indicators of meat from broilers given Moringa oleifera leaf meal. South African Journal of Animal Science, 43(Supp. 1), 43-47.
Wen-qian, J. and Fu-chang, L. 2010.Effects of Dietary Lysine on Growth Performance, Serum Concentrations of Insulin-Like Growth Factor-I (IGF-I) and IGF-I mRNA Expression
in Growing Rabbits.Agricultural Sciences in China, 9(6): 887-895.
Wood, J. D., Richardson, R. I., Nute, G. R., Fisher, A. V., Campo, M. M., Kasapidou, E., Sheard, P. R and Enser, M. 2003. Effects of fatty acids on meat quality: a review. Meat Science, 66: 21-32.
17 CHAPTER 2: Literature Review
2.1 Introduction
World pork production has been on the rise over the last few decades as there have been
increases in both the number of pigs produced and the animal slaughter weights (Cameron,
2000). The demand for pork has risen during the last few decades because there has been an
increase in income in developing countries with fast growing economies, causing an increase
in the demand for meat (FAO, 2011). Other reasons for the increasing global demand for
pork include the rapid rate of increase of human population worldwide and improving human
nutritional aspirations (Kyriazakis and Whittemore, 2006). The world‟s population has
increased by a billion people every decade over the last three decades and this sharp increase
in population has caused a significant rise in the demand, production and consumption of
meat (Rosegrant et al., 2001).
Production traits such as growth rate, feed conversion efficiency and carcass leanness are of
great economic importance for pig producers; and for pork processors, the carcass weight,
carcass leanness, proportions of primal and sub-primal cuts and processing yields are traits of
economic importance (Barbut et al., 2008). Issues of importance regarding the quality of pork
for consumers are traits such as colour, drip loss, tenderness, juiciness, aroma and flavour, as
well as the nutritional composition of pork and its health implications. Currently, focus is
being placed on the development of the functional value of meat for promotion of health and
disease prevention, and this can amongst others, be achieved by adding to animal diets
compounds such as vitamin E, selenium, omega 3 fatty acids andconjugated linoleic acid
18
Moringa oleifera Lam, commonly referred to as Drumstick tree, Horseradish tree and often
simply called moringa,is a small to medium sized deciduous tree originally from India,
Pakistan and Nepal (Sidduhraju and Becker, 2003). Moringa has now become naturalised to
many tropical and sub-tropical regions of Asia, Africa, South and Central America, the
Caribbean Islands, the Mediterranean and the Arabian Peninsula, and it is being propagated
and cultivated in most counties across the globe (HDRA, 2002; ECHO, 2007;Roloff et al.,
2009).M. oleifera Lam is a drought resistant species able to withstand high temperatures
ranging from 40ºC - 48ºC (HDRA, 2002) and capable of tolerating a wide range of soil types
and rainfall conditions (Iqbal and Bhanger, 2006), but it is sensitive to water logging, so it
grows better in well drained soils (FAO, 2007). Aside from being valued for its hardiness and
ability to survive in a wide range of climatic conditions including drought, M. oleifera is
highly valued because it is a multipurpose tree (Makkar and Becker, 1997; Foidl et al., 2001;
HDRA, 2002).M. oleifera is considered to be one of the most valuable plants on earth (NRC, 2006) and is referred to by many as “the miracle tree” (Ashraf and Gilani, 2007), “the tree of
life” (Djakalia et al., 2011), and as “nature‟s medicine cabinet” (Paliwal et al., 2011) because
of its nutritional and medicinal benefits. Moringa is also known by numerous vernacular
names in different countries, an indication of its prominence and significance in many
countries worldwide (Sutherland, 1996).Moringa was previously an unknown plant species
but in the last three decades, it has been the focus of much research, beginning in the 1980s
with studies on its water treatment properties and expanding over the next two decades into
its use for food and its medicinal properties, attracting the attention and investment of many
NGOs because of its potential to contribute to poverty reduction and reduce malnutrition
(Sauveur and Broin, 2010). The hardiness of the M. oleifera tree, wide range of products that
19 improvement of both small and large scale agricultural production and this has sparked
interest in its use for rural development (Sutherland, 1996).
2.2 Uses of Moringa oleifera in agriculture
Moringa oleifera Lam has several industrial, nutritional and medicinal uses (Makkar and
Becker, 1997). All parts of the tree, which includes the leaves, pods, seeds, flowers and roots are used in traditional medicine (Hirt and M‟pia, 2008). This is because extracts from all
parts of Moringa oleifera Lam plants have pharmalogical properties, evidenced by the history
of their use in many regions for this purpose and corroborated by the scientific community
through research. In many countries around the world,M. oleifera has been used as a natural
medicine, as various parts of the tree possess anti-inflammatory and anti-bacterial properties
(HDRA, 2002). M. oleifera is frequently used in traditional Asian and West African medicine
(Roloff et al., 2009). M. oleifera, seeds, pods and roots can be used for human consumption
and the residue left over from extraction of oil and coagulants from seeds are good sources of
protein for animal feeds (Makkar and Becker, 1997). M. oleifera seeds have coagulant
properties suitable for water purification.
The leaves of M. oleifera are the parts which are most commonly used (HDRA, 2002). M.
oleifera leaves have high nutritional value as well as antibacterial, antihelmintic and
antioxidant properties and can be used to improve animal growth performance, reduce
internal parasite infestations, improve meat quality and improve the nutritional composition
of the meat. Reyez-Sánchez et al. (2005) reported that the supplementation of dairy cows
with M. Oleifera leaves resulted in a significant increase in daily milk yield. Moyo et al.
20 peroxidation in liver from goats supplemented with M. Oleifera leaves due to the high
phenolic and flavonoid content of M. Oleifera. Qwele et al. (2013) also reported an increase
in the antioxidant activity of meat from goats supplemented with M. Oleifera leaves and
attributed this increase to the high levels of natural antioxidants (vitamin E, vitamin C,
phenols and flavonoids) present in M. Oleifera leaves. The nutritional composition of goat
meat from goats fed M. Oleifera supplemented diets was more favourable, with higher
amounts of crude protein, lower levels of cholesterol, higher levels of n-3 fatty acids and a
higher antioxidant activity than those fed the control diet.
2.3 Nutritional composition of Moringa oleiferaleaves
M. oleifera leaves are known to be highly nutritious, as they contain a rich and rare
combination of nutrients, amino acids and antioxidants (Mahmood et al., 2009). Moringa
leaves contain high levels of protein, minerals, and vitamins with notably high levels of
vitamins A, C and E, as well as beta carotene, thiamin and riboflavin (Roloff et al., 2009).
They are a rich source of carotenoids, ascorbic acid and iron (Ritcher et al., 2003). Makkar
and Becker (1997) found that the crude protein content of leaves was 260 gkg-1 (26%), of which 87% was in the form of true protein and only 3% was insoluble in the acid detergent
fibre component and was consequently unavailable to animals. Moringa leaves contain all of
the essential amino acids at levels comparable to that of soyabeans. Moringa contains high
levels of the sulphur containing amino acids methionine and cystine (Foidl et al., 2001). In
terms of anti-nutritional factors, Makkar and Becker (1997) reported that the leaves had
negligible amounts (12gkg-1or 1.2%) of tannins, a phytate content of 21gkg-1 (2.1%) and a saponin content of 80gkg-1 (8%) as diosgenin equivalent that did not show any haemolytic activity. Tannins are natural water-soluble phenolic compounds that bind with proteins
21 forming stable complexes that are not easily degraded (Waterman, 2000), thus reducing the
amount of protein available for utilisation by the ingesting animal. Makkar and Becker (1997)
reported that they were unable to detect any trypsin and amylase inhibitors, lectins,
cyanogenic glucosides and glucosinolates. The nutrient composition of Moringa leaves has
been analysed in several studies, the results of which are summarised in Table 2.1.
M. oleifera leaves are reportedly a rich source of protein, ß-carotene, vitamin E, vitamin C,
calcium, and potassium. Furthermore they are a source of natural antioxidant compounds such as α-tocopherol, ascorbic acid, flavonoids, phenolics and carotenoids, which are able to
slow down oxidation and enhance the shelf life of fat containing foods (Anwar et al., 2007).
Siddhuraju and Becker (2003) found that M. oleifera leaves exhibit marked antioxidant
activity and are a potential source of natural antioxidants. Moringa leaves can be used as a
protein source for livestock production (Mendieta-Araica et al., 2011). Several studies have
evaluated the use of M. oleifera for feeding livestock species including pigs, chickens, goats,
sheep, dairy cows; as well as some species of fish. Results from these studies have shown that
M. oleifera can constitute up to 10% of pig diets (Acda et al., 2010), up to 10% of Nile tilapia
feed (Ritcher et al., 2009) and up to 60% of dairy cow concentrates. It can also be used as a
22
Table 2.1 Nutrient composition of Moringa oleifera leaves
Nutrient Reference
Moyo et al., 2011 Afuang et al., 2003 Ritcher et al., 2003
DM % 90.5 93.7 93.8
Crude protein % 30.29 25.4 25.0
Fat % 6.50 4.6 -
Ash % 7.64 9.0 8.4
Neutral Detergent Fibre % 11.40 29.1 15.9
Acid Detergent Fibre % 8.49 4.4 12.6
Acid Detergent Lignin % 1.80 1.5 -
Acid Detergent Cellulose % 4.01 - -
Condensed tannins (mg/g) 3.12 1.2 0.5
23 2.4 Effect of nutrition on pig production and pork quality
Animal nutrition is a critical component in livestock production partly because the cost of
feeding livestock amounts to 60-75% of total production costs (Lammers et al., 2007;
SAPPO, 2007; Bhat et al., 2010;) and also because nutrition has a major influence on the
productivity of the animals in terms of their growth, health, reproduction and the quality of
the products derived from them. Most pig producers adopt feeding strategies that aim to
maximise economic efficiency by providing the essential nutrients at levels as close to the animals‟ requirements as possible (Bhat et al., 2010) so as not to cause costly wastages by
overfeeding or reductions in productivity by underfeeding.
2.4.1 Growth
All species of animals undergo an increase in size and weight over time which can be termed
as growth, as well as changes in body shape, conformation and the function of some organs
and systems which can be termed as development (Lawrie and Ledward, 2006).The
hormones responsible for regulating growth are influenced by genetic, nutritive and
environmental factors (Hossner, 2005). Therefore the growth rate of pigs is resultant from
the interaction of genetic, management and environmental factors including nutrition,
genotype, parental age and size, age and sex of the individual animal and environmental
temperatures (Lynch et al.,2006; Bhat et al., 2010).Nutrition is one of the main determinants
of animal growth because the provision of adequate nutrition has a direct effect on the
realisation of genetic growth potential (Wen-qian and Fu-chang, 2010). Hossner (2005)
reported that of all the factors that influence animal growth, nutrition arguably has the
greatest effect since the amount and quality of feed is the most important factor in the
regulation of growth rate.This is evidenced by studies in which animals of the same breed and
24 planes of nutrition (Lawrie and Ledward, 2006). Various nutrients have different ways by
which they influence growth.
The essential nutrients required by pigs are water, amino acids, fatty acids, macro and micro
minerals, vitamins and carbohydrates (Lammers et al., 2007; Novak et al., 2007). Pigs at
different stages of growth and during different stages of production have different nutrient
requirements. The main factors that influence the nutrient requirements of pigs are age, sex,
development stage, breed, genetic strain, heterosis, environmental temperature, humidity and
the health status of the animal (Rostagno et al., 2005;SAPPO, 2007; Bhat et al., 2010).
Animal feed intake is dependent not only on their nutritional requirements, but also on the
quality of the feed in terms of the availability and digestibility of dietary nutrients as well as
the presence of moulds, toxins or inhibitors (Bhat et al., 2010). The energy level of feed also
influences feed intake. When growing pigs are given ad libitum access to feed, their feed
intake and feed conversion depends on the energy level of the feed (Rostagno et al., 2005).
The energy requirement of growing/finishing pigs is governed by the need to promote protein
deposition for maximum lean meat with adequate intramuscular fat (Varley and Wiseman,
2001).
The level of protein in feed plays a significant role in animal growth, as the main function of
protein in the body is growth. Amino acids are used to build muscle tissue (Lammers et al.,
2007). Adequate amino acid intake is required in order to maximise protein accretion rate and
growth rate; inadequate levels of amino acids would result in slower growth rates and
produce carcasses with more fat (Pettigrew and Esnaola, 2001). Dietary amino acid
restriction, however, produces carcasses with more marbling (Pettigrew and Esnaola, 2001;
25 are not the only nutrients involved in or responsible for growth. The consumption of both energy and amino acids is required for the deposition of protein in the animal‟s body such
that a limitation of energy and increase of amino acid levels in the diet does not increase
protein deposition and likewise, limitation of amino acids and increased levels of energy in
the diet does not increase protein deposition but does increase fat deposition (Pettigrew and
Esnaola, 2001). This is because when more energy than is needed for protein deposition is
consumed, it is converted to and stored as fat.
2.4.2 Carcass characteristics
Pigs are more efficient carcass yielders than most other livestock species, dressing out about
70% in comparison with 50-55% in cattle and around 50% in sheep and goats (Ikani and
Dafwang, 1995). In growing/finishing pigs, manipulation of the diet is an effective way of
achieving desirable carcass composition. The level of protein and energy in the diet has a
major effect on the lean: fat composition of the meat produced. One of the nutrients that has
an effect on carcass composition is the essential mineral chromium. Chromium increases the effect of insulin‟s regulation of blood glucose and can increase the rate of lean deposition in
meat (Dugan et al.,2004). Favourable biological responses to chromium supplementation,
such as improvements in the function of insulin, have been observed in growing and
reproducing pigs (Lindemann, 1995; Pettigrewand Esnaola, 2001).
2.4.3 Meat quality
Meat quality is a broad concept that includes eating quality aspects such as appearance,
flavour, tenderness and juiciness; physico-chemical aspects such as pH, water holding
capacity, fatty acid composition and oxidative stability; as well as nutritional composition,
health implications and ethical acceptability (Anderson, 2000).Physico-chemical traits are
26 may have an effect on the further processing of meat, such as thawing loss and cooking loss.
As with growth performance, meat quality is also influenced by a number of factors including
genetics, animal nutrition, animal handling during transportation, prior to and during
slaughter and the handling of the carcass (Pettigrew and Esnaola, 2001; Dugan et al., 2003).
In response to consumers‟ growing meat quality demands, the meat industry is continually
taking measures to improve the tenderness, juiciness and flavour of pork and to reduce
incidences of pale, soft, exudative (PSE) meat conditions (Barbut et al., 2008). PSE meat
occurs when the muscle pH declines too rapidly to levels of 5.5 - 5.7 within 45 min or less of
slaughter and to a very low ultimate pH of pH <5.4. This negatively affects meat quality, as
PSE meat has a pale appearance, lower water retaining potential and may be more susceptible
to bacteriological spoilage (Lammers et al., 2007). According to Pettigrew and Esnaola
(2001) nutrition can be used to improve pork quality. Diet composition and feed consumption
has an effect on the chemical composition of muscle tissue and on aspects of meat quality
such as pH, colour, water holding capacity, tenderness, juiciness, flavour and aroma.
2.4.3.1 pH and colour
Meat pH is the measure of the acidity and the alkalinity of meat, and has an effect on the
colour and water retaining properties of the meat, as well as the shelf life and susceptibility of
meat to bacteriological spoilage. The normal pH decline in muscles is from approximately
7.0- 7.2 down to near 5.5- 5.7 over 24 hrs post mortem (Hambrecht et al., 2004). However, if
the pH declines to the normal pH of 5.5 - 5.7 within 45 min or less of slaughter, the muscle
will appear very pale and soft (PSE) and a very low ultimate pH (<5.4) will also result in a
paler colour (Lammers et al., 2007). According to Barbut et al.(2008), pH and temperature
are indisputably two of the main factors that contribute to protein denaturation and the
27 2.4.3.2 Water holding capacity and juiciness
The water holding capacity of meat can be defined as its ability to retain water when exposed
to pressure and/orheat. In fresh meat that has not been extensively processed, it is often
described as the drip loss or purge. After freezing meat, the loss of moisture during defrosting
is known as the thawing loss and the extent to which meat is able to retain water during
cooking is measured by the cooking loss. Juiciness of meat depends on the amount of water
retained in a cooked meat product. Juiciness increases flavour and helps soften meat making
it easier to chew, and stimulates saliva production in the mouth. Water retention and lipid
content determine juiciness, as marbling and fat around edges of meat helps hold in water. An
example of a nutrient that influences water holding capacity and consequently juiciness is
magnesium. Supplementation of magnesium can also improve pork quality by reducing drip loss and paleness (D‟Souza et al.,1998; Frederick and van Heugten, 2003). Magnesium has
the potential to reduce the rate of glycolysis that are triggered by stress hormones shortly
after slaughter, thereby preventing accelerated post mortem glycolysis of the warm carcass,
lactic acid build-up, pH drop and development of pale, soft, exudative (PSE) pork (Dugan et
al., 2004).
2.4.3.3 Tenderness, flavour and aroma
Sensory characteristics of pork such as tenderness, flavour and aroma are critical factors that
determine the eating pleasure of consumers and can influence decisions on future purchasing
intent and consumption of pork. Once meat has been cooked, consumer satisfaction largely
depends on the tenderness of the meat and its flavour, aroma and juiciness (Glitsch, 2000).
According to Warner et al. (2010), meat tenderness is determined by factors such as the
amount and solubility of connective tissue, sarcomere shortening during rigor development,
28 energy metabolism. The streaks of fat that occur between the bundles of muscle fibre on a
piece of meat are known as intramuscular fat and is commonly referred to as marbling
(Lammers et al., 2007). Marbling provides much of the flavour in pork and contributes to the
tenderness of the meat.
2.5 Fat composition
There have been many studies and much media coverage over the past decade concerning
health and safety issues of the human diet. It has emerged that meat is a major dietary source
of saturated fatty acids (SFAs) (Walker et al., 2005) which have been implicated in
increasing the risk of coronary heart diseases, diabetes mellitus, stroke and some cancers
(Wood et al., 2003; Walker et al., 2005). Consumers of meat are consequently concerned
about the composition of meat fat. According to Wood et al. (2003) the recommended ratio
of polyunsaturated fatty acids:saturated fatty acids (PUFA:SFA) in the diet should be higher
than 0.4. Pigs have highlevels of polyunsaturated fatty acids (PUFA), including the long
chain (C20-22) PUFA in adipose tissue and muscle (Wood et al. 2008). The ratio of
PUFA:SFA in pig meat is 0.7 (Kyriazakis and Whittemore, 2006) which is well above the
recommended value. More recently however, nutritionists have placed emphasis on the type
of PUFA in the diet, specifically the balance between n-3 PUFA (α-linolenic acid, 18:3n3)
and n-6 PUFA (linoleic acid, 18:2n6) because the ratio of n-6:n-3 PUFA is also a risk factor
in cancers and coronary heart disease and the formation of blood clots leading to heart attack
(Enser, 2001; Wood et al.,2003). It is recommended that the ratio of n-6:n-3 in the human
diet should be less than 4.0 but pig meat has an average ratio of 7.0, as the PUFA in pig meat
consists mainly of n-6 PUFA (Kyriazakis and Whittemore, 2006). As a result of these issues
29 general public for meat with less saturated fatty acids (Mas et al., 2010) and higher levels of
n-3 PUFA (Wood et al., 2003).
According to Mapiye et al.(2012), although pork and other red meats have been stigmatised
for fat composition and its link to increased risk of cardiovascular diseases and cancer, the
composition of meat fat is one of the few factors that can be modified. Research in swine
nutrition has shown that the fatty acid profile of pork fat can be altered by feeding pigs diets
containing different fatty acid concentrations (Mas et al.,2010; Rentfrow et al., 2003). The
ratios of both PUFA:SFA and n-6:n-3 can be manipulated towards more favourable values by
altering their concentrations in the animal‟s diet (Wood et al.,2003). Meat from monogastric
animals such as pigs naturally has a relatively low conjugated linoleic acid (CLA) content but
it is possible to increase this through increasing the levels of CLA in the pigs diet (Simpson,
2009).
Besides having health implications, fatty acid composition of meat is also an issue of
importance because fatty acids have an influence on some technological aspects of meat
quality such as fat tissue firmness, shelf life and flavour. Fatty acids have different melting
points and consequently have a major influence on the firmness or softness of the
subcutaneous, intermuscular and intramuscular fat (Wood et al., 2003).Additionally, fatty
acid composition determines the firmness/oiliness of adipose tissue and the oxidative stability
of muscle, which in turn affects flavour and muscle colour (Wood et al., 2008).As such,
through the manipulation of the fatty acid composition of pig diets, these technological
aspects of meat quality can be improved. Mapiye et al.(2012) propose that altering the fatty
acid composition also creates the opportunity for beneficially enhancing the nutritional
30 functional value of meat for promotion of health and disease prevention, and this can be
achieved by adding to animal diets compounds such as vitamin E, selenium, omega 3 fatty
acids and conjugated linoleic acid (Wangang et al., 2010)
2.6Shelf life
Oxidative stability of meat refers to the susceptibility of the lipids in meat to oxidation and is
majorly influenced by the degree of saturation of the lipids. Pork naturally has a high PUFA
content and meat that has a more unsaturated fatty acid profile may have a shorter shelf life
period because unsaturated fatty acids are more susceptible to oxidation and lipid oxidation
causes off-odours, off-flavours and impaired meat colour (Wood et al., 2003; Haak et al.,
2008).
Vitamin E is known to be a natural antioxidant, and feeding diets high in or supplementing
with vitamin E increases the oxidative stability of pork (Dugan et al.,2004). According to
Hasty et al.(2002), while the extensive studies that have been carried out on the effect of
vitamin E on meat quality have shown varying results for its effect on colour and drip loss,
the improvement of oxidative stability in these studies has been consistent.
2.7 Consumer perception and preferences on pork
Consumer food choices are influenced not only by the price and physical attributes of the
product at the point of purchase but also by the attitudes that consumers have towards the
product, which results from the interaction of a number of factors. Some of the factors that
influence choices in the purchase of meat products are the physical attributes of the product,
health concerns, convenience, the need for variety and ethical and environmental issues
31 suitability of a product to meet their needs, it is also strongly influenced by psychological
perceptions about the product (Troy and Kerry, 2010).
Perception of a product can be described as the light in which one views the product or the
attitude that a person has towards the product based on the knowledge or information that the
person knows or has heard about that product. Consumer perception on meat goes beyond the
attributes of appearance, smell, taste and flavour because perceptions are also formed based
on knowledge and experiences which incorporates a complex combination of learning,
motivational and contextual factors (Troy and Kerry, 2010). Consumer perception of meat is
said to be based on intrinsic quality cues which are formed based on the physical attributes of
the product and extrinsic quality cues which are formed based on the knowledge of health,
cultural, ethical and environmental issues (Grunert, 2006).Consumer perception of meat
quality is largely based on intrinsic cues such as meat colour and the amount of visible fat.
Meat is usually an unbranded product and there is limited information available at the point
of purchase about the extrinsic cues of the production processes that the animal went through
during rearing and the environment that it was reared in (Grunert, 2006). In the past few
decades, however, emphasis has been placed on traceability of meat products in order to
make available to the consumers information on extrinsic cues. Branding of meat products is also an emerging trend. Namibia‟s FAN (Farm Assured Namibian) Meat Scheme is an
example of this as is the newly registered brand “Karoo lamb”. Meat produced within these
schemes are traceable back to the farms where they were produced (which facilitates
accountability on animal welfare issues), is branded, uniformly packaged and the packaging
contains information on the production system used (eg free range); due to this form of
branding, Namibian meat is exported to the EU where it is highly sought after (Meatco,
32 The perception that consumers have toward meat is of critical importance and has a direct
effect on the profitability of the meat industry because sales depend upon consumer
willingness to purchase and consume meat products and a positive perception towards meat is
required for this (Troy and Kerry, 2010). The main concern for meat consumers is not only
on value for money but is also on health implications because of the subsequent effect that
food consumption has on health, morbidity and mortality (Sorbal et al., 2006).
2.7.1 Health implications of pork consumption
Food choices are important decisions for consumers because they determine the types and
quantities of nutrients and substances that individuals consume. Consumers have become
increasingly conscious about dietary health issues because of the large amount of scientific
evidence linking food consumption to health risks, which has led to growing interest in media
coverage and public opinion on the relationship between diet and health (Jiménez-Colmenero
et al., 2001). Health implications from the consumption of meat arise from two general
sources, namely the nutritional composition of the meat and food borne health risks of meat
that occur as a result of zoonotic diseases and contamination of meat by harmful pathogens
(Verbeke et al., 1999). Nutritional health implications of meat consumption are largely linked
to its fat content. Negative effects on human health due to fat consumption occur as a result
of both the quantity and type of fats consumed. Inclusion of high levels of fat in the human
diet can lead to excessive weight gain and overweight individuals are at an increased risk of
the occurrence of health problems such as type 2 diabetes, cardiovascular diseases, and high
blood pressure (NHS, 2011). The degree of un-saturation of fatty acids has also been
identified as a potential health risk because it has an effect on the type of cholesterol found in
33 the favourable form, or as Low Density Lipoprotein (LDL) and Very Low Density
Lipoprotein (VLDL) which are the unfavourable forms. Saturated fats generally have high
levels of LDL-cholesterol and increase the risk of cardiovascular diseases, with the exception
of Saturated Fatty Acids (SFA) with 18 or more carbon atoms in their chains as these long
chain SFAs have higher levels of HDL-cholesterol (Verbeke et al., 1999).
Health implications of meat consumption also include the potential risk of contracting
zoonotic diseases; which are diseases that can be transferred from animals to
humans.Salmonella is one of the most important food borne pathogens in the swine industry
and over the last decade 4.5 – 23% of worldwide salmonellosis occurrences in humans have
been as a result of pork consumption (Poljak, 2009). Another example of a zoonotic diseaseis
bovine spongiform encephalopathy (BSE) which is commonly known as mad cow disease
(Jiménez-Colmenero et al., 2001) although pigs are not carriers of this disease.
Health and safety characteristics of meat cannot easily be inferred at purchase by intrinsic
characteristics and requires knowledge of extrinsic characteristics (Grunert, 2006). There are
exceptions, however, such as the colour and smell of meat that can be used by consumers as
an indicator of its freshness and suitability for consumption, but generally consumers gain
information on health implications from health experts, the media and public opinion. It is a
combination of the physical characteristics of pork and the information known about pork that forms consumers‟ perception towards pork.
2.7.2 Consumer perceptions on pork
Generally, consumers perceive pork to be less healthy and contain more fat than other kinds
34 formation of perceptions towards meat because of the health implications that arise from fat
consumption. Of all the types of red meat, lamb has the highest levels of separable fat,
followed by pork, however after removal of separable fat the fat content of the lean muscle is
lowest in pork (Verbeke et al., 1999). Therefore the fat content of lean pork with low levels
of visible fat actually contains less fat than other types of red meat.
Appearance criteria are important in choosing pork and have a great influence on consumer
purchasing attitudes towards pork (Dransfield et al., 2006; Fortomaris et al., 2006).
Dransfield et al.(2005) reported that consumers from four countries, namely France, Demark,
Sweeden and UK, use the aspects of colour and fatness rather than marbling and drip loss as
the basis for their choice to purchase and consume pork. According to Fortomaris et al.
(2006), this may be due to the fact that there is a high level of inconsistency amongst
consumers in the choices for marbling and drip loss, illustrating that these characteristics can
be considered as less helpful in consumer choice.The effect that perception of pork has on the
demand for pork creates an importance for the pork industry to be consumer driven and it is
in the best interest of all parties involved for the consumer preferences on pork to be
established and addressed (Ngapo et al., 2007).
2.7.3 Consumer preferences on pork
Consumers prefer pork with high levels of juiciness, flavour and tenderness, as well as
uniformity in the product. Consequently, unacceptable levels of juiciness, tenderness, flavour
and large variability in product quality is expected to impact negatively on the repetitive
purchasing behaviour of consumers (Verbeke et al., 1999). In terms of appearance, the
factors that consumers take into account are the colour, the drip loss and the amount of
35 Ngapo et al.(2007) surveyed 12 590 consumers from 23 countries and found that preferences
varied considerably between different individuals, groups, and countries but that there was an
overall preference for light to dark red coloured pork with low levels of visible fat and no
drip loss. Consumer preferences on pork fat are largely formed on the basis of dietary
guidelines on fat consumption. It has been recommended by the World Health Organisation
(WHO) that fat should provide only 15-30% of the total calories consumed daily, of which
saturated fats should provide no more than 10% and cholesterol intake should be limited to
300mg/day (Jiménez-Colmenero et al., 2001). Hence consumers prefer pork which is lean
and which has minimal visible fat. Furthermore, the WHO limitations on fat consumption are
set not only for the amount of fat consumed but also the fatty acid composition and level of
cholesterol consumed. Concerning the fatty acid profile of pork, consumers prefer that the
amount of PUFA in pork increase, with a specific preference for higher levels of n-3 fatty
acids, and the amount of SFA be decreased; or alternatively for an increase in the MUFA
content because they play a protective role against cardiovascular diseases, evidenced by the
low rate of cardiovascular disease occurrence in individuals who consume high levels of
olive oil, which is rich in MUFAs (Verbeke et al., 1999). Besides these intrinsic cues,
consumers also have preferences based on the extrinsic cues which are concerned with the
production environment.
Nowadays the majority of commercial pig production is done intensively and this raises
concern amongst consumers about safety, animal welfare and environmental pollution
(Dransfield et al., 2005). According to Grunert (2006), anearlier study found that German
pork consumers ranked animal friendly farm, animal friendly transportation, stunning before
slaughter, fat percentage of meat and no use of GMO feed as their top five important extrinsic
36 consideration consumer perceptions and preferences for pork in order to produce products
that will satisfy these consumer needs.Many studies have been carried out on ways to
improve consumer perception on meat in terms of quality, safety and product stability, the
results of which have been implemented by the meat industry (Troy and Kerry, 2010). Figure
2.1 illustrates the various avenues that can be exploited in order to address the concerns
37 Figure 2.1Possibilities to improve characteristics, consumer perception and acceptability of pork.
